1. Field of the Invention
The present invention relates to an alignment correction method for a substrate to be exposed, and to an exposure apparatus, which correct an alignment deviation occurring at a substrate to be exposed that has been aligned to a photomask, and more specifically, relates to an alignment correction method for a substrate to be exposed, and to an exposure apparatus, which correct alignment of a subsequent substrate to be exposed based on a correction amount computed from an alignment deviation of a previously exposed substrate to be exposed, to thereby enhance alignment accuracy.
2. Description of Related Art
A conventional alignment correction method for a substrate to be exposed is such that by using an image-capturing device having a plurality of light-receiving elements linearly arranged in a direction perpendicular to a scanning direction of the substrate to be exposed, an image of a plurality of rectangular pixels formed on the substrate to be exposed is captured; a position of a left side edge of a left-most pixel of the substrate to be exposed is detected based on brightness information of the captured image; a position deviation amount between the position of the left side edge of the leftmost pixel and a reference position set in advance in the image capturing device is computed; and a photomask is moved in a direction perpendicular to the scanning direction of the substrate to be exposed so as to correct the position deviation amount, to thereby align the photomask to the substrate to be exposed (for example, refer to Japanese Laid-Open (Kokai) Patent Application Publication No. 2008-76709).
However, in the above conventional alignment correction method for a substrate to be exposed, since correction of alignment of the substrate to be exposed is performed each time the substrate to be exposed arrives and its alignment deviation is detected, if the position of a camera for alignment mark detection is shifted due to, for example, deformation of an exposure apparatus caused by heat and alignment accuracy of the substrate to be exposed is deteriorated before exposure, there is not enough time to correct the alignment, and defective exposure may occur.